Hydrocarbon conversion process using zeolite SSZ-32 as catalyst

ABSTRACT

A crystalline zeolite SSZ-32 of novel composition is prepared using an N-lower alkyl-N&#39;-isopropyl-imidazolium cation as a template. Also disclosed is a process for converting hydrocarbons with crystalline zeolite SSZ-32.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a division of application Ser. No. 07/723,236, filedJun. 28, 1991, now U.S. Pat. No. 5,252,527, which is in turn acontinuation of application Ser. No. 433,382, filed Oct. 24, 1989 (nowU.S. Pat. No. 5,053,373), which is in turn a continuation of applicationSer. No. 172,730, filed Mar. 23, 1988 (abandoned).

BACKGROUND OF THE INVENTION

Natural and synthetic zeolitic crystalline aluminosilicates are usefulas catalysts and adsorbents. These aluminosilicates have distinctcrystal structures which are demonstrated by X-ray diffraction. Thecrystal structure defines cavities and pores which are characteristic ofthe different species. The adsorptive and catalytic properties of eachcrystalline aluminosilicate are determined in part by the dimensions ofits pores and cavities. Thus, the utility of a particular zeolite in aparticular application depends at least partly on its crystal structure.

Because of their unique molecular sieving characteristics, as well astheir catalytic properties, crystalline aluminosilicates are especiallyuseful in such applications as gas drying and separation and hydrocarbonconversion. Although many different crystalline aluminosilicates andsilicates have been disclosed, there is a continuing need for newzeolites and silicates with desirable properties for gas separation anddrying, hydrocarbon and chemical conversions, and other applications.

Crystalline aluminosilicates are usually prepared from aqueous reactionmixtures containing alkali or alkaline earth metal oxides, silica, andalumina. "Nitrogenous zeolites" have been prepared from reactionmixtures containing an organic templating agent, usually anitrogen-containing organic cation. By varying the synthesis conditionsand the composition of the reaction mixture, different zeolites can beformed using the same templating agent. Use of N,N,N-trimethylcyclopentylammonium iodide in the preparation of Zeolite SSZ-15molecular sieve is disclosed in U.S. Pat. No. 4,610,854; use of1-azoniaspiro [4.4] nonyl bromide and N,N,N-trimethyl neopentylammoniumiodide in the preparation of a molecular sieve termed "Losod" isdisclosed in Helv. Chim. Acta (1974), Vol. 57, page 1533 (W. Sieber andW. M. Meier); use of quinuclidinium compounds to prepare a zeolitetermed "NU-3" is disclosed in European Pat. Publication No. 40016; useof 1,4-di(1-azoniabicyclo [2.2.2.]octane) lower alkyl compounds in thepreparation of Zeolite SSZ-16 molecular sieve is disclosed in U.S. Pat.No. 4,508,837; use of N,N,N-trialkyl-1-adamantamine to in thepreparation of zeolite SSZ-13 molecular sieve is disclosed in U.S. Pat.No. 4,544,538. The preparation of crystalline aluminosilicates using animidazole template is disclosed in U.S. Pat. No. 4,483,835.

SUMMARY OF THE INVENTION

We have prepared a family of crystalline aluminosilicate molecularsieves with unique properties, referred to herein as "Zeolite SSZ-32" ofnovel composition, and have found a highly effective method forpreparing SSZ-32. Such novel SSZ-32 has a mole ratio of silicon oxide toaluminum oxide in the range of 20 to less than 40, and has the X-raydiffraction lines of Table 1 below. Novel zeolite SSZ-32 has essentiallythe same X-ray diffraction pattern as ZSM-23, described in U.S. Pat. No.4,076,842. In the present invention the aluminum content is higher thanpreviously described. The X-ray diffraction lines are quite broad due tothe very small crystal size.

As has been shown before, aluminum can be a crystallization inhibitorduring the synthesis of pentasil zeolites. Sand and coworkers have shownthat crystallization rates for ZSM-5 are lowered by increasing aluminumcontent (Zeolites 1983 pg. 155). For some pentasil zeolites sufficientquantities of aluminum prevent crystallization entirely, establishing alower boundary for SiO₂ /Al₂ O₃ values. In other instances, a differentzeolite is obtained at a certain SiO₂ /Al₂ O₃ ratio. In the case of thesystem cited above for ZSM-23, a lower SiO₂ /Al₂ O₃ is establishedwherein the ratio is equal to or greater than 40. Attempts to obtainZSM-23 having a lower SiO₂ /Al₂ O₃ resulted in the formation of ZSM-35,a synthetic ferrierite (U.S. Pat. No. 4,016,245, Ex. 18-25).

The product of the present invention is found to be substantially moreselective than previously described ZSM-23 zeolites which possess higherSiO₂ /Al₂ O₃ values and larger crystals. This leads to novel, beneficialcatalytic uses for SSZ-32. The novel zeolite SSZ-32 further has acomposition, as synthesized and in the anhydrous state, in terms of moleratios of oxides as follows: (0.05 to 2.0)Q₂ O: (0.1 to 2.0)M₂ O:Al₂ O₃:(20 to less than 40)SiO₂ wherein M is an alkali metal cation, and Q isan N-lower alkyl-N'-isopropyl-imidazolium cation and preferably anN,N'-diisopropyl-imidazolium cation, orN-methyl-N'-isopropyl-imidazolium cation. The zeolite can have a YO₂ :W₂O₃ mole ratio in the range of 20 to less than 40 (ZSM-23 as made hasvalues ≧40). As prepared, the silica:alumina mole ratio is typically inthe range of 25:1 to about 37:1. Higher mole ratios can be obtained bytreating the zeolite with chelating agents or acids to extract aluminumfrom the zeolite lattice. The silica:alumina mole ratio can also beincreased by using silicon and carbon halides and other similarcompounds.

Our invention also involves a method for preparing those zeolites,comprising preparing an aqueous mixture containing sources of N-loweralkyl-N'-isopropylimidazolium cation and preferablyN,N'-diisopropylimidazolium or N-methyl-N'-isopropyl-imidazolium, anoxide of aluminum, and an oxide of silicon, and having a composition, interms of mole ratios of oxides, falling within the following ranges:SiO₂ /Al₂ O₃, 20:1 to less than 40:1; and Q/SiO₂, 0.05:1 to 0.50:1, andQ is N-lower alkyl-N'-isopropyl-imidazolium cation and preferablyN,N'-diisopropyl-imidazolium cation or N-methyl-N'-isopropyl-imidazoliumcation; maintaining the mixture at a temperature of at least 100° C.until the crystals of said zeolite are formed; and recovering saidcrystals.

Preferably, the aluminum oxide source provides aluminum oxide which isin a covalently dispersed form on silica, i.e., the aluminum atoms arecovalently bonded through oxygen atoms to silicon. The preferredaluminum oxide source seems to slow down the formation of otherzeolite-type impurities.

DETAILED DESCRIPTION OF THE INVENTION

Novel SSZ-32 zeolites, as synthesized, have a crystalline structurewhose X-ray powder diffraction pattern shows the followingcharacteristic lines:

                  TABLE 1                                                         ______________________________________                                               d/n   Int. I/I.sub.o                                                   ______________________________________                                               11.05 26                                                                      10.05 10                                                                      7.83  17                                                                      4.545 71                                                                      4.277 71                                                                      3.915 100                                                                     3.726 98                                                               ______________________________________                                    

The X-ray powder diffraction patterns were determined by standardtechniques. The radiation was the K-alpha/doublet of copper and ascintillation counter spectrometer with a strip-chart pen recorder wasused. The peak heights I and the positions, as a function of 2 θ where θis the Bragg angle, were read from the spectrometer chart. From thesemeasured values, the relative intensities, 100I/I_(o), where I_(o) isthe intensity of the strongest line or peak, and d, the interplanarspacing in Angstroms corresponding to the recorded lines, can becalculated. The X-ray diffraction pattern of Table 1 is characteristicof novel SSZ-32 zeolites. The zeolite produced by exchanging the metalor other cations present in the zeolite with various other cationsyields substantially the same diffraction pattern although there can beminor shifts in interplanar spacing and minor variations in relativeintensity. Minor variations in the diffraction pattern can also resultfrom variations in the organic compound used in the preparation and fromvariations in the silica-to-alumina mole ratio from sample to sample.Calcination can also cause minor shifts in the X-ray diffractionpattern. Notwithstanding these minor perturbations, the basic crystallattice structure remains unchanged.

Novel SSZ-32 zeolites can be suitably prepared from an aqueous solutioncontaining sources of an alkali metal oxide, N-loweralkyl-N'-isopropyl-imidazolium cation and preferablyN,N'-diisopropyl-imidazolium cation or N-methyl-N'-isopropyl-imidazoliumcation, an oxide of aluminum, and preferably wherein the aluminum oxidesource provides aluminum oxide which is in a covalently dispersed formon silica, and an oxide of silicon. The reaction mixture should have acomposition in terms of mole ratios falling within the following ranges:

    ______________________________________                                                    Broad     Preferred                                               ______________________________________                                        SiO.sub.2 /Al.sub.2 O.sub.3                                                                 20-less than 40                                                                           30-35                                               OH.sup.- /SiO.sub.2                                                                         0.10-1.0    0.20-0.40                                           Q/SiO.sub.2   0.05-0.50   0.10-0.20                                           M.sup.+ /SiO.sub.2                                                                          0.05-0.30   0.15-0.30                                           H.sub.2 O/SiO.sub.2                                                                          20-300     25-60                                               Q/Q + M.sup.+ 0.25-0.75   0.33-0.67                                           ______________________________________                                    

wherein Q is an N-lower alkyl-N'-isopropyl-imidazolium cation andpreferably an N,N'-diisopropyl-imidazolium cation orN-methyl-N'-isopropyl-imidazolium cation. M is an alkali metal ion,preferably sodium or potassium. The organic cation compound which actsas a source of the quaternary ammonium ion employed can providehydroxide ion.

The cation component Q, of the crystallization mixture, is preferablyderived from a compound of the formula ##STR1## wherein R is lower alkylcontaining 1 to 5 carbon atoms and preferably CH₃, or ##STR2## andA.sup.θ is an anion which is not detrimental to the formation of thezeolite. Representative of the anions include halogens, e.g., fluoride,chloride, bromide and iodide, hydroxide, acetate, sulfate, carboxylate,etc. Hydroxide is the most preferred anion.

The reaction mixture is prepared using standard zeolitic preparationtechniques. Typical sources of aluminum oxide for the reaction mixtureinclude aluminates, alumina, and aluminum compounds, such asaluminum-coated silica colloids, Al₂ (SO₄)₃, and other zeolites.

In a preferred method of preparing zeolite SSZ-32, we have found thatproviding sources of aluminum oxide to a zeolite synthesis mixturewherein the aluminum oxide is in a covalently dispersed form on silicaallows zeolites with increased aluminum content to be crystallized. Inone preferred approach zeolites of pentasil structure and lower SiO₂/Al₂ O₃ values (approximately 10) can be used as aluminum oxide sourcesor feedstocks for the synthesis of zeolite SSZ-32. These zeolites arerecrystallized to the new SSZ-32 zeolite in the presence of the cationcomponent Q defined above. Mordenite and ferrierite zeolites constitutetwo such useful sources of aluminum oxide or feedstocks. These latterzeolites have also been used in the crystallization of ZSM-5 and ZSM-11(U.S. Pat. No. 4,503,024). In another preferred approach wherein thealuminum oxide is in a covalently dispersed form on silica is to use analumina coated silica sol such as that manufactured by Nalco Chem. Co.under the product name 1SJ612 (26% SiO₂, 4% Al₂ O₃). This sol isparticularly useful in producing very small crystals with high catalyticactivity. In addition to providing novel SSZ-32 with high aluminumcontent, use of the sol generates crystallites of less than 1000 Å(along the principal axis) with surprisingly high shape selectivity.

Indeed, the catalytic performance of SSZ-32, in the hydrogen form, issuch that high conversions can be obtained while the shape selectivityis manifested by Constraint Index values (as defined in J. Catalysis 67,page 218) of 13 or greater and preferably from 13 to 16. Determinationof Constraint index is also disclosed in U.S. Pat. No. 4,481,177. Ingeneral, lowering the crystallite size of a zeolite may lead todecreased shape selectivity. This has been demonstrated for ZSM-5reactions involving aromatics as shown in J. Catalysis 99,327 (1986). Inaddition, a zeolite ZSM-22, (U.S. Pat. No. 4,481,177) has been found tobe closely related to ZSM-23 (i. Chem. Soc. Chem. Comm. 1985 page 1117).In the above reference on ZSM-22 it was shown that ball-milling thecrystallites produced a catalyst with a constraint index of 2.6. This isa surprisingly low value for this material given other studies whichindicate that it is a very selective 10-ring pentasil (Proc. of 7thIntl. Zeolite Conf. Tokyo, 1986, page 23). Presumably the ball-millingleads to a less selective but more active catalyst, by virtue ofproducing smaller crystallites.

In this regard it is quite surprising to find that novel zeolite SSZ-32shows such high shape selectivity, given its high catalytic activity andvery small crystallite size.

Typical sources of silicon oxide include silicates, silica hydrogel,silicic acid, colloidal silica, fumed silicas, tetraalkylorthosilicates, and silica hydroxides. Salts, particularly alkali metalhalides such as sodium chloride, can be added to or formed in thereaction mixture. They are disclosed in the literature as aiding thecrystallization of zeolites while preventing silica occlusion in thelattice.

The reaction mixture is maintained at an elevated temperature until thecrystals of the zeolite are formed. The temperatures during thehydrothermal crystallization step are typically maintained from about140° C. to about 200° C., preferably from about 160° C. to about 180° C.and most preferably from about 170° C. to about 180° C. Thecrystallization period is typically greater than 1 day and preferablyfrom about 5 days to about 10 days.

The hydrothermal crystallization is conducted under pressure and usuallyin an autoclave so that the reaction mixture is subject to autogenouspressure. The reaction mixture can be stirred during crystallization.

Once the zeolite crystals have formed, the solid product is separatedfrom the reaction mixture by standard mechanical separation techniquessuch as filtration. The crystals are water-washed and then dried, e.g.,at 90° C. to 150° C. for from 8 to 24 hours, to obtain the assynthesized, zeolite crystals. The drying step can be performed atatmospheric or subatmospheric pressures.

During the hydrothermal crystallization step, the crystals can beallowed to nucleate spontaneously from the reaction mixture. Thereaction mixture can also be seeded with SSZ-32 or ZSM-23 crystals bothto direct, and accelerate the crystallization, as well as to minimizethe formation of undesired aluminosilicate contaminants. If the reactionmixture is seeded with crystals, the concentration of the organiccompound can be reduced, but it is preferred to have some organiccompound present, e.g., an alcohol.

The synthetic zeolites can be used as synthesized or can be thermallytreated (calcined). Usually, it is desirable to remove the alkali metalcation by ion exchange and replace it with hydrogen, ammonium, or anydesired metal ion. The zeolite can be leached with chelating agents,e.g., EDTA or dilute acid solutions, to increase the silica:alumina moleratio. The zeolite can also be steamed; steaming helps stabilize thecrystalline lattice to attack from acids. The zeolite can be used inintimate combination with hydrogenating components, such as tungsten,vanadium, molybdenum, rhenium, nickel, cobalt, chromium, manganese, or anoble metal, such as palladium or platinum, for those applications inwhich a hydrogenation-dehydrogenation function is desired. Typicalreplacing cations can include metal cations, e.g., rare earth, Group IIAand Group VIII metals, as well as their mixtures. Of the replacingmetallic cations, cations of metals such as rare earth, Mn, Ca, Mg, Zn,Cd, Pt, Pd, Ni, Co, Ti, Al, Sn, Fe and Co are particularly preferred.

The hydrogen, ammonium, and metal components can be exchanged into thezeolite. The zeolite can also be impregnated with the metals, or, themetals can be physically intimately admixed with the zeolite usingstandard methods known to the art. And, the metals can be occluded inthe crystal lattice by having the desired metals present as ions in thereaction mixture from which the SSZ-32 zeolite is prepared.

Typical ion exchange techniques involve contacting the synthetic zeolitewith a solution containing a salt of the desired replacing cation orcations. Although a wide variety of salts can be employed, chlorides andother halides, nitrates, and sulfates are particularly preferred.Representative ion exchange techniques are disclosed in a wide varietyof patents including U.S. Pat. Nos. 3,140,249; 3,140,251; and 3,140,253.Ion exchange can take place either before or after the zeolite iscalcined.

Following contact with the salt solution of the desired replacingcation, the zeolite is typically washed with water and dried attemperatures ranging from 65° C. to about 315° C. After washing, thezeolite can be calcined in air or inert gas at temperatures ranging fromabout 200° C. to 820° C. for periods of time ranging from 1 to 48 hours,or more, to produce a catalytically active product especially useful inhydrocarbon conversion processes.

Regardless of the cations present in the synthesized form of thezeolite, the spatial arrangement of the atoms which form the basiccrystal lattice of the zeolite remains essentially unchanged. Theexchange of cations has little, if any, effect on the zeolite latticestructures.

The aluminosilicate can be formed into a wide variety of physicalshapes. Generally speaking, the zeolite can be in the form of a powder,a granule, or a molded product, such as extrudate having particle sizesufficient to pass through a 2-mesh (Tyler) screen and be retained on a400-mesh (Tyler) screen. In cases where the catalyst is molded, such asby extrusion with an organic binder, the aluminosilicate can be extrudedbefore drying, or, dried or partially dried and then extruded. Thezeolite can be composited with other materials resistant to thetemperatures and other conditions employed in organic conversionprocesses. Such matrix materials include active and inactive materialsand synthetic or naturally occurring zeolites as well as inorganicmaterials such as clays, silica and metal oxides. The latter may occurnaturally or may be in the form of gelatinous precipitates, sols, orgels, including mixtures of silica and metal oxides. Use of an activematerial in conjunction with the synthetic zeolite, i.e., combined withit, tends to improve the conversion and selectivity of the catalyst incertain organic conversion processes. Inactive materials can suitablyserve as diluents to control the amount of conversion in a given processso that products can be obtained economically without using other meansfor controlling the rate of reaction. Frequently, zeolite materials havebeen incorporated into naturally occurring clays, e.g., bentonite andkaolin. These materials#i.e., clays, oxides, etc., function, in part, asbinders for the catalyst. It is desirable to provide a catalyst havinggood crush strength, because in petroleum refining the catalyst is oftensubjected to rough handling. This tends to break the catalyst down intopowders which cause problems in processing.

Naturally occurring clays which can be composited with the syntheticzeolites of this invention include the montmorillonite and kaolinfamilies, which families include the sub-bentonites and the kaolinscommonly known as Dixie, McNamee, Georgia and Florida clays or others inwhich the main mineral constituent is halloysite, kaolinite, dickite,nacrite, or anauxite. Fibrous clays such as sepiolite and attapulgitecan also be used as supports. Such clays can be used in the raw state asoriginally mined or can be initially subjected to calcination, acidtreatment or chemical modification.

In addition to the foregoing materials, the SSZ-32 zeolites can becomposited with porous matrix materials and mixtures of matrix materialssuch as silica, alumina, titania, magnesia, silica:alumina,silica-maghesia, silica-zirconia, silica-thoria, silica-beryllia,silica-titania, titania-zirconia as well as ternary compositions such assilica-alumina-thoria, silica-alumina-zirconia, silica-alumina-magnesiaand silica-magnesia-zirconia. The matrix can be in the form of a cogel.

The SSZ-32 zeolites can also be composited with other zeolites such assynthetic and natural faujasites (e.g., X and Y), erionites, andmordenites. They can also be composited with purely synthetic zeolitessuch as those of the ZSM series. The combination of zeolites can also becomposited in a porous inorganic matrix.

Novel SSZ-32 zeolites are useful in hydrocarbon conversion reactions.Hydrocarbon conversion reactions are chemical and catalytic processes inwhich carbon containing compounds are changed to different carboncontaining compounds. Examples of hydrocarbon conversion reactionsinclude catalytic cracking, hydrocracking, and olefin and aromaticsformation reactions, including formation from oxygenates. The catalystsare useful in other petroleum refining and hydrocarbon conversionreactions such as isomerizing n-paraffins and naphthenes, polymerizingand oligomerizing olefinic or acetylenic compounds such as isobutyleneand butene-1, reforming, alkylating, isomerizing polyalkyl substitutedaromatics (e.g., meta xylene), and disproportionating aromatics (e.g.,toluene) to provide mixtures of benzene, xylenes and highermethylbenzenes.

Novel SSZ-32 zeolites can be used in processing hydrocarbonaceousfeedstocks. Hydrocarbonaceous feedstocks contain carbon compounds andcan be from many afferent sources, such as virgin petroleum fractions,recycle petroleum fractions, shale oil, liquefied coal, tar sand oil,and, in general, can be any carbon containing fluid susceptible tozeolitic catalytic reactions. Depending on the type of processing thehydrocarbonaceous feed is to undergo, the feed can contain metal or befree of metals, it can also have high or low nitrogen or sulfurimpurities. It can be appreciated, however, that in general processingwill be more efficient (and the catalyst more active) the lower themetal, nitrogen, and sulfur content of the feedstock.

The conversion of hydrocarbonaceous feeds can take place in anyconvenient mode, for example, in fluidized bed, moving bed, or fixed bedreactors depending on the types of process desired. The formulation ofthe catalyst particles will vary depending on the conversion process andmethod of operation.

Other reactions which can be performed using the catalyst of thisinvention containing a metal, e.g., platinum, includehydrogenation-dehydrogenation reactions, denitrogenation anddesulfurization reactions.

Novel SSZ-32 can be used in hydrocarbon conversion reactions with activeor inactive supports, with organic or inorganic binders, and with andwithout added metals. These reactions are well known to the art, as arethe reaction conditions.

SSZ-32 can be used to dewax hydrocarbonaceous feeds by selectivelyremoving straight chain paraffins. The catalytic dewaxing conditions aredependent in large measure on the feed used and upon the desired pourpoint. Generally, the temperature will be between about 200° C. andabout 475° C., preferably between about 250° C. and about 450° C. Thepressure is typically between about 15 psig and about 3000 psig,preferably between about 200 psig and 3000 psig. The liquid hourly spacevelocity (LHSV) preferably will be from 0.1 to 20, preferably betweenabout 0.2 and about 10.

Hydrogen is preferably present in the reaction zone during the catalyticdewaxing process. The hydrogen to feed ratio is typically between about500 and about 30,000 SCF/bbl (standard cubic feet per barrel),preferably about 1000 to about 20,000 SCF/bbl. Generally, hydrogen willbe separated from the product and recycled to the reaction zone. Typicalfeedstocks include light gas oil, heavy gas oils and reduced crudesboiling about 350° F.

The SSZ-32 hydrodewaxing catalyst may optionally contain a hydrogenationcomponent of the type commonly employed in dewaxing catalysts. Thehydrogenation component may be selected from the group of hydrogenationcatalysts consisting of one or more metals of Group VIB and Group VIII,including the salts, complexes and solutions containing such metals. Thepreferred hydrogenation catalyst is at least one of the group of metals,salts and complexes selected from the group consisting of at least oneof platinum, palladium, rhodium, iridium and mixtures thereof or atleast one from the group consisting of nickel, molybdenum, cobalt,tungsten, titanium, chromium and mixtures thereof. Reference to thecatalytically active metal or metals is intended to encompass such metalor metals in the elemental state or in some form such as an oxide,sulfide, halide, carboxylate and the like.

The hydrogenation component is present in an effective amount to providean effective hydrodewaxing catalyst preferably in the range of fromabout 0.05 to 5% by weight.

SSZ-32 can be used to convert light straight run naphthas and similarmixtures to highly aromatic mixtures. Thus, normal and slightly branchedchained hydrocarbons, preferably having a boiling range above about 40°C. and less than about 200° C., can be converted to products having asubstantial higher octane aromatics content by contacting thehydrocarbon feed with the zeolite at a temperature in the range of fromabout 400° C. to 600° C., preferably 480°C.-550° C. at pressures rangingfrom atmospheric to 10 bar, and liquid hourly space velocities (LHSV)ranging from 0.1 to 15.

The conversion catalyst preferably contains a Group VIII metal compoundto have sufficient activity for commercial use. By Group VIII metalcompound as used herein is meant the metal itself or a compound thereof.The Group VIII noble metals and their compounds, platinum, palladium,and iridium, or combinations thereof can be used. Rhenium or tin or amixture thereof may also be used in conjunction with the Group III metalcompound and preferably a noble metal compound. The most preferred metalis platinum. The amount of Group VIII metal present in the conversioncatalyst should be within the normal range of use in reformingcatalysts, from about 0.05 to 2.0 weight percent, preferably 0.2 to 0.8weight percent.

The zeolite/Group VIII metal conversion catalyst can be used without abinder or matrix. The preferred inorganic matrix, where one is used, isa silica-based binder such as Cab-O-Sil or Ludox. Other matrices such asmagnesia and titania can be used. The preferred inorganic matrix isnonacidic.

It is critical to the selective production of aromatics in usefulquantities that the conversion catalyst be substantially free ofacidity, for example by poisoning the zeolite with a basic metal, e.g.,alkali metal, compound. The zeolite is usually prepared from mixturescontaining alkali metal hydroxides and thus have alkali metal contentsof about 1-2 weight percent. These high levels of alkali metal, usuallysodium or potassium, are unacceptable for most catalytic applicationsbecause they greatly deactivate the catalyst for cracking reactions.Usually, the alkali metal is removed to low levels by ion-exchange withhydrogen or ammonium ions. By alkali metal compound as used herein ismeant elemental or ionic alkali metals or their basic compounds.Surprisingly, unless the zeolite itself is substantially free ofacidity, the basic compound is required in the present process to directthe synthetic reactions to aromatics production.

The amount of alkali metal necessary to render the zeolite substantiallyfree of acidity can be calculated using standard techniques based on thealuminum content of the zeolite. Under normal circumstances, the zeoliteas prepared and without ion-exchange will contain sufficient alkalimetal to neutralize the acidity of the catalyst. If a zeolite free ofalkali metal is the starting material, alkali metal ions can be ionexchanged into the zeolite to substantially eliminate the acidity of thezeolite. An alkali metal content of about 100%, or greater, of the acidsites calculated on a molar basis is sufficient. Similar considerationsare in order for alkaline earth cations.

Where the basic metal content is less than 100% of the acid sites on amolar basis, the test described in U.S. Pat. No. 4,347,394 which patentis incorporated totally herein by reference, can be used to determine ifthe zeolite is substantially free of acidity.

The preferred alkali metals are sodium and potassium. The zeolite itselfcan be substantially free of acidity only at very high silica:aluminamol ratios; by "zeolite consisting essentially of silica" is meant azeolite which is substantially free of acidity without base poisoning.

Hydrocarbon cracking stocks can be catalytically cracked in the absenceof hydrogen using SSZ-32 at liquid hourly space velocities from 0.5 to50, temperatures from about 260° F. to 1625° F. and pressures fromsubatmospheric to several hundred atmospheres, typically from aboutatmospheric to about 5 atmospheres.

For this purpose, the SSZ-32 catalyst can be composited with mixtures ofinorganic oxide supports as well as traditional cracking catalyst.

The catalyst may be employed in conjunction with traditional crackingcatalysts, e.g., any aluminosilicate heretofore employed as a componentin cracking catalysts. Representative of the zeolitic aluminosilicatesdisclosed heretofore as employable as component parts of crackingcatalysts are Zeolite Y (including steam stabilized chemically modified,e.g., ultra-stable Y), Zeolite X, Zeolite beta (U.S. Pat. No.3,308,069), Zeolite ZK-20 (U.S. Pat. No. 3,445,727), Zeolite ZSM-3 (U.S.Pat. No. 3,415,736), faujasite, LZ-10 (U.K. Pat. 2,014,970, Jun. 9,1982), ZSM-5-type zeolites, e.g., ZSM-5, ZSM-11, ZSM-12, ZSM-23, ZSM-35,ZSM-38, ZSM-48, crystalline silicates such as silicalite (U.S. Pat. No.4,061,724), erionite, mordenite, offretite, chabazite, FU-1-typezeolite, NU-type zeolites, LZ-210-type zeolite and mixtures thereof.Traditional cracking catalysts containing amounts of Na₂ O less thanabout one percent by weight are generally preferred. The relativeamounts of the SSZ-32 component and traditional cracking component, ifany, will depend at least in part, on the selected hydrocarbon feedstockand on the desired product distribution to be obtained therefrom, but inall instances an effective amount of SSZ-32 is employed. When atraditional cracking catalyst (TC) component is employed the relativeweight ratio of the TC to the SSZ-32 is generally between about 1:10 andabout 500:1, desirably between about 1:10 and about 200:1, preferablybetween about 1:2 and about 50:1, and most preferably is between about1:1 and about 20:1.

The cracking catalysts are typically employed with an inorganic oxidematrix component which may be any of the inorganic oxide matrixcomponents which have been employed heretofore in the formulation of FCCcatalysts including: amorphous catalytic inorganic oxides, e.g.,catalytically active silica-aluminas, clays, silicas, aluminas,silica-aluminas, silica-zirconias, silicamagnesias, alumina-borias,alumina-titanias and the like and mixtures thereof. The traditionalcracking component and SSZ-32 may be mixed separately with the matrixcomponent and then mixed or the TC component and SSZ-32 may be mixed andthen formed with the matrix component.

The mixture of a traditional cracking catalyst and SSZ-32 may be carriedout in any manner which results in the coincident presence of such incontact with the crude oil feedstock under catalytic crackingconditions. For example, a catalyst may be employed containing thetraditional cracking catalyst and a SSZ-32 in single catalyst particlesor SSZ-32 with or without a matrix component may be added as a discretecomponent to a traditional cracking catalyst.

SSZ-32 is especially useful as a catalyst in a process for isomerizingone or more xylene isomers in a C₈ aromatic feed to obtain ortho-, meta-and pars-xylene in a ratio approaching the equilibrium value. Inparticular, xylene isomerization is used in conjunction with aseparation process to manufacture pars-xylene. For example, a portion ofthe pars-xylene in a mixed C₈ aromatics stream may be recovered bycrystallization and centrifugation. The mother liquor from thecrystallizer is then reacted under xylene isomerization conditions torestore ortho-, meta-, and pars-xylenes to a near equilibrium ratio. Atthe same time, part of the ethylbenzene in the mother liquor isconverted to xylenes or to products which are easily separated bydistillation. The isomerate is blended with fresh feed and the combinedstream is distilled to removed heavy and light by-products. Theresultant C₈ aromatics stream is then sent to the crystallizer to repeatthe cycle.

Xylene isomerization catalysts are judged on their ability to produce anear equilibrium mixture of xylenes and convert ethylbenzene with verylittle net loss of xylenes. The SSZ-32 type zeolites are especiallyeffective in this regard. Accordingly, an additional aspect of thepresent invention is to provide a hydrocarbon conversion process whichcomprises contacting a C₈ aromatic stream containing one or more xyleneisomers or ethylbenzene or a mixture thereof, under isomerizationconditions with a catalyst comprising SSZ-32.

The SSZ-32 may conveniently be used as an aggregate in the form ofpellets or extrudates. An inorganic oxide binder such as gamma aluminaor silica may be employed to provide attrition resistance.

In the vapor phase, suitable isomerization conditions include atemperature in the range 500°-1100° F., preferably 600°-1050° F., apressure in the range 0.5-50 atm abs, preferably 1-5 atm abs, and aweight hourly space velocity (WHSV) of 0.1 to 100, preferably 0.5 to 50.Optionally, isomerization in the vapor phase is conducted in thepresence of 3.0 to 30.0 moles of hydrogen per mole of alkylbenzene. Ifhydrogen is used the catalyst should comprise 0.1 to 2.0 wt % of ahydrogenation/dehydrogenation component selected from Group VIII of thePeriodic Table, especially platinum, palladium or nickel. By Group VIIImetal component is meant the metals and their compounds such as oxidesand sulfides.

In the liquid phase, suitable isomerization conditions include atemperature in the range 100°-700° F., a pressure in the range 1-200 atmabs, and a WHSV in the range 0.5-50. Optionally, the isomerization feedmay contain 10 to 90 wt % of a diluent such as toluene,trimethylbenzenes, naphthenes or paraffins.

SSZ-32 can also be used to oligomerize straight and branched chainolefins having from about 2 to 21 and preferably 2-5 carbon atoms. Theoligomers which are the products of the process are medium to heavyolefins which are useful for both fuels, i.e., gasoline or a gasolineblending stock and chemicals.

The oligomerization process comprises contacting the olefin feedstock inthe gaseous state phase with SSZ-32 at a temperature of from about 450°F. to about 1200° F., a WHSV of from about 0.2 to about 50 and ahydrocarbon partial pressure of from about 0.1 to about 50 atmospheres.

Also, temperatures below about 450OF may be used to oligomerize thefeedstock, when the feedstock is in the liquid phase when contacting thezeolite catalyst. Thus, when the olefin feedstock contacts the zeolitecatalyst in the liquid phase, temperatures of from about 50OF to about450° F., and preferably from 80° to 400° F. may be used and a WHSV offrom about 0.05 to 20 and preferably 0.1 to 10. it will be appreciatedthat the pressures employed must be sufficient to maintain the system inthe liquid phase. As is known in the art, the pressure will be afunction of the number of carbon atoms of the feed olefin and thetemperature. Suitable pressures include from about 0 psig to about 3000psig.

The zeolite can have the original cations associated therewith replacedby a wide variety of other cations according to techniques well known inthe art. Typical cations would include hydrogen, ammonium and metalcations including mixtures of the same. Of the replacing metalliccations, particular preference is given to cations of metals such asrare earth metals, manganese, calcium, as well as metals of Group II ofthe Periodic Table, e.g., zinc, and Group VIII of the Periodic Table,e.g., nickel. One of the prime requisites is that the zeolite have afairly low aromatization activity, i.e., in which the amount ofaromatics produced is not more than about 20% by weight. This isaccomplished by using a zeolite with controlled acid activity [alphavalue]of from about 0.1 to about 120, preferably from about 0.1 to about100, as measured by its ability to crack n-hexane.

Alpha value are defined by a standard test known in the art, e.g., asshown in U.S. Pat. No. 3,960,978 which is incorporated totally herein byreference. If required, such zeolites may be obtained by steaming, byuse in a conversion process or by any other method which may occur toone skilled in this art.

SSZ-32 can be used to convert light gas C₂ -C₆ paraffins and/or olefinsto higher molecular weight hydrocarbons including aromatic compounds.Operating temperatures of 100°C.-700° C., operating pressures of 0 to1000 psig and space velocities of 0.5-40 hr⁻¹ WHSV (weight hourly spacevelocity) can be used to convert the C₂ -C₆ paraffin and/or olefins toaromatic compounds. Preferably, the zeolite will contain a catalystmetal or metal oxide wherein said metal is selected from the groupconsisting of Group IB, IIB, VIII and IIIA of the Periodic Table, andmost preferably gallium or zinc and in the range of from about 0.05 to5% by weight.

SSZ-32 can be used to condense lower aliphatic alcohols having 1 to 8carbon atoms to a gasoline boiling point hydrocarbon product comprisingmixed aliphatic and aromatic hydrocarbon. The condensation reactionproceeds at a temperature of about 500° F. to 1000° F., a pressure ofabout 0.5 to 1000 psig and a space velocity of about 0.5 to 50 WHSV. Theprocess disclosed in U.S. Pat. No. 3,984,107 more specifically describesthe process conditions used in this process, which patent isincorporated totally herein by reference.

The catalyst may be in the hydrogen form or may be base exchanged orimpregnated to contain ammonium or a metal cation complement, preferablyin the range of from about 0.05 to 5% by weight. The metal cations thatmay be present include any of the metals of the Groups I through VIII ofthe Periodic Table. However, in the case of Group IA metals the cationcontent should in no case be so large as to effectively inactivate thecatalyst.

The product of this invention can also be used as an adsorbent, as afiller in paper, paint, and toothpastes, and as a water-softening agentin detergents.

The following are examples for the synthesis and characterization ofnovel zeolite SSZ-32 composition.

EXAMPLES Example 1

18.73 Grams of a 0.78 M solution of N,N'-diisopropyl-imidazoliumhydroxide were mixed with 44 ml of H₂ O and 1.06 gms of NAOH (solid).The organocation is prepared as described in U.S. Pat. No. 4,483,835. Itis then ion-exchanged to its hydroxide form using AGl-X8 resin. 22.16Grams of Ludox AS-30 are blended into the above solution. After thoroughmixing, 10.96 gms of Nalco 1SJ612 (26% SiO₂ 4% Al₂ O₃) were added withmixing. Finally, milligram quantities of crystalline ZSM-23, prepared asin Example 31 of U.S. Pat. No. 4,483,835, were added to the mix asseeds. The reaction solution was stirred at 30 RPM and heated to 170° C.for 7 days. Upon washing, drying and X-ray diffraction analysis, thereaction product was crystalline SSZ-32.

Example 2

Another reaction was run as in Example 1, adding in sequence, 0.24 gmsof NAOH, 7 ml H₂ O, 4.0 gms of the template solution of Example 1, 4.0gms of Ludox AS-30, and 2.55 gms of Nalco ISJ612. Seeds from Example 1were added and the reaction was run as in Example 1. The product wasonce again crystalline SSZ-32. Analysis showed the SiO₂ /Al₂ O₃ ratio tobe 39.

Example 3

While the use of the colloidal silica with aluminum dispersed on it(Nalco 1SJ612) is helpful in obtaining SSZ-32 zeolite with enhanced Al₂O₃ content, other sources of aluminum can be used. A particularlyinteresting way to disperse aluminum is to use it already incorporatedinto a zeolite as feedstock. Thus, aluminum was supplied as NortonFerrierite (SiO₂ /Al₂ O₃ =10). 208 Grams of the hydroxide template fromExample 1 was mixed with 0.93 grams of NAOH, and 13.2 grams ofFerrierite. 78 Grams of Ludox AS-30 were blended in and the reactionmixture was placed in a 600 cc reactor, stirred at 69 RPM, and heatedfor 8 days at 175° C. The product was crystalline SSZ-32 with noFerrierite detected. Analysis showed the SiO₂ /Al₂ O₃ ratio to be 32.

Example 4

A reaction similar to that in Example 3 was set up except theorganocation used was N-methyl-N'-isopropylimidazolium as prepared inU.S. Pat. No. 4,483,835 and ion-exchanged to its hydroxide form.Synthesis at 160° C. and 30 RPM for 6 days produced SSZ-32 zeolitewithout Ferrierite as a secondary phase.

Example 5

3.25 Grams of N,N'-diisopropyl-imidazolium hydroxide (0.80M), 0.26 gmsof NAOH and 7.15 ml H₂ O were combined. 0.55 Grams of Al₂ (SO₄)₃.18H₂ Owas dissolved and finally 6.5 gms of Ludox AS-30 was blended in and amagnetic teflon-coated stir bar was placed in the teflon reactor withthe reactants. The reactor was tumbled at 30 RPM while being heated to170° C. for 10 days. The crystalline product after work-up and analysiswas SSZ-32 with a trace of mordenite. The SiO₂ /Al₂ O₃ ratio of thesolids was 35.

Example 6

A reactant mixture was prepared from 33 gms of the template solutionused in the previous example, 2.21 gms NAOH, 2.04 gms Na₂ O Al₂ O₃ 3H₂O, 64 ml H₂ O, and finally 65 gms of Ludox AS-30. Seeds of ZSM-23 (0.5gms) as prepared by the method of U.S. Pat. No. 4,483,835 were added.The reactant SiO₂ /Al₂ O₃ ratio was 35 and the synthesis was carried outat 170° C. for 7 days at 50 RPM. The product was SSZ-32 with a smallamount of mordenite.

Example 7

A solution is made up by mixing 3.79 gms of NaOH(solid), 122 ml H₂ O,and 53 gms of a 15.5% solution of the N,N'-diisopropyl-imidazoliumhydroxide. 65 Grams of Ludox AS-30 is added. After thorough mixing,aliquots of 16.36 gms of this solution are transferred to the tefloncups of Parr 4745 reactors. 2.74 Grams of Nalco 1SJ612 are added to eachcup with stirring and the contents are heated at 170° C. for 6 days with30 RPM tumbling. The product was identified as pure SSZ-32. ICP chemicalanalysis showed the product to have an SiO₂ /Al₂ O₃ ratio of 32.7. Therepresentative X-ray diffraction pattern of the as made material istabulated in Table 2 below.

                  TABLE 2                                                         ______________________________________                                        2Θ                                                                             d/n          Int          100 × I/I.sub.o                        ______________________________________                                         8.00  11.05        15            26                                           8.80  10.05         6            10                                          11.30  7.83         10            17                                          14.50  6.11          1            2                                           15.75  5.63          3            5                                           16.50  5.37          3            5                                           18.10  4.901         7            12                                          19.53  4.545        41            71                                          20.05  4.428         6shoulder    10shoulder                                  20.77  4.277        41            71                                          21.30  4.171         7            12                                          22.71  3.915        58           100                                          23.88  3.726        57            98                                          24.57  3.623        30            52                                          25.08  3.551        25            43                                          25.88  3.443        27            47                                          26.88  3.317         5            9                                           28.11  3.174         6            10                                          ______________________________________                                    

Example 8

The zeolite products of Examples 1-7 were calcined as follows. In a thinbed, the zeolite was brought to 540° C. over a 7-hour period in amixture of air and nitrogen. The calcination was maintained at 540° C.for 4 hours and then raised to 600° C. and kept there for 4 more hours.If all carbonaceous material was still not removed, the temperature wasbrought to 650° C. for several hours. Each sample was then subjected toa sequence of 4 NH₄ NO₃ ion-exchanges in a 1M solution, each for 2 hoursat 100° C. Finally, the dried exchanged zeolite was calcined at 540° C.for several hours to produce the acidic form of the zeolite.

Example 9

The hydrogen form of the SSZ-32 powder from Example 2 (treated accordingto Example 8) was placed in 1/4" reactor tube and heated to 500° C. A1/1 v/v n-hexane/3-methyl-pentane feed was passed over the catalyst atan LHSV of 1. At 10 minutes on stream and at 800° F. the conversion wasfound to be 48% with a constraint index of 14.2, thus demonstrating thenovel shape selective properties of the SSZ-32 described herein.

Example 10

The same catalytic evaluation carried out in Example 9 was repeated thistime using the crystalline product of Example 7. The conversion was now55% at 10 minutes on stream and the constraint index was 16.

Example 11

The catalyst used in Example 10 was employed for conversion of methanolto hydrocarbons. At 10 minutes on stream the conversion was 100% at 700°F. with the products mainly distributed between C₃ to C₈ with olefins,saturates and aromatics having been formed.

Example 12

A sample of zeolite H⁺ SSZ-32 prepared according to Examples 7 and 8 wastested for xylene isomerization activity as follows. The pure zeolitepowder was formed into pellets using a hydraulic press. The pellets werethen crushed and sieved to obtain 20-40 mesh granules which were thencalcined for four hours. One gram of the calcined material was thencharged to a 3/16-inch I.D. tubular microreactor heated by an electricfurnace. The catalyst bed was heated to 800° F. in flowing helium. Thehelium was then replaced with a mixed xylene feed. The feed compositionand reactor effluent were analyzed by gas chromatography. Table 3 showsthat the zeolite H+SSZ-32 produced a near equilibrium mixture ofxylenes. Better than 30% ethylbenzene conversion was obtained with onlya small net loss of xylenes.

                  TABLE 3                                                         ______________________________________                                        Xylene Isomerization Over Zeolite H.sup.+ SSZ-32                                               Feed Products                                                ______________________________________                                        Temperature, °F.   800                                                 WHSV                      5                                                   Pressure, psig            25                                                  Composition, Wt %                                                             non-aromatics      1.4    2.1                                                 benzene            0.0    2.2                                                 toluene            1.3    2.9                                                 ethylbenzene       9.7    6.7                                                 p-xylene           9.5    19.6                                                m-xylene           53.1   43.3                                                o-xylene           22.9   19.7                                                heavy aromatics    2.1    3.7                                                 Percent EB Conversion     30.9                                                Percent Xylene Loss       3.3                                                 p-xylene % approach       102                                                 to equilibrium                                                                ______________________________________                                    

EXAMPLE 13

SSZ-32 powder from Examples 7 and 8, and treated according to Example 8,was ion-exchanged with palladium as follows.

Four (4) grams of the product of Example 7 following Example 8 treatmentwas slurried into 43 ml H₂ O and the pH was brought to 9.5 with NH₄ OH.0.069 Grams of Pd(NH₃)₄.2NO₃ in 6 ml. H₂ O with pH adjusted to 9.5 also(NH₄ OH) was added slowly and stirred overnight at room temperature. Thesolids are then filtered, washed, and dried.

The ion-exchanged powder was formed into tablets which were crushed andsieved to obtain 20-40 mesh granules for testing in a microreactor. Thegranular catalyst was activated by calcination in air at 250° F. to 900°F. over a period of eight hours followed by reduction of the palladiumin flowing hydrogen at 900° F. The catalyst was tested as described inthe previous example except that the xylene isomerization process wascarried out at 150 psig in the presence of hydrogen.

The reaction conditions and results are shown in Table 4. As in theprevious example, SSZ-32 was shown to produce an equilibrium mixture ofxylenes with only a small net xylene loss at better than 30%ethylbenzene conversion. The presence of hydrogen and a hydrogenationcatalyst (i.e., Pd) was found to inhibit catalyst fouling and greatlyincrease run length compared to the previous example.

                  TABLE 4                                                         ______________________________________                                        Xylene Isomerization Over                                                     Palladium Ion-Exchanged SSZ-32                                                                 Feed Products                                                ______________________________________                                        Temperature, °F.   800                                                 WHSV of xylene feed       5                                                   Pressure, psig            150                                                 H.sub.2 /xylene molar ratio                                                                             10                                                  Composition, Wt %                                                             Non-aromatics      1.4    2.7                                                 Benzene            0.0    2.1                                                 Toluene            1.3    2.9                                                 Ethylbenzene       9.7    6.4                                                 P-xylene           9.5    19.6                                                M-xylene           53.1   43.4                                                O-xylene           22.9   19.5                                                Heavy aromatics    2.1    3.4                                                 Percent EB Conversion     32.6                                                Percent Xylene Loss       3.5                                                 P-xylene % approach to    102                                                 equilibrium                                                                   ______________________________________                                    

What is claimed is:
 1. A process for converting hydrocarbons comprisingcontacting a hydrocarbonaceous feed at hydrocarbon converting conditionswith a zeolite having a mole ratio of silicon oxide to aluminum oxidegreater than about 20:1 to less than 40:1, and having the X-raydiffraction lines of Table
 1. 2. The process of claim 1 wherein saidprocess is a hydrocracking process comprising contacting the hydrocarbonfeedstock under hydrocracking conditions with said zeolite.
 3. Theprocess of claim 1 wherein said process is a dewaxing process comprisingcontacting the hydrocarbon feedstock under dewaxing conditions with saidzeolite.
 4. The process of claim 1 wherein said process is a process forpreparing a high octane product having an increased aromatics contentcomprising:(a) contacting a hydrocarbonaceous feed which comprisesnormal and slightly branched hydrocarbons having a boiling range aboveabout 40° C. and less than about 200° C., under aromatic conversionconditions with said zeolite, wherein said zeolite is substantially freeof acidity; and (b) recovering a higher octane, higher aromaticeffluent.
 5. The process of claim 4 wherein the zeolite contains a GroupVIII metal component.
 6. The process of claim 1 wherein said process isa catalytic cracking process comprising the step of contacting thehydrocarbon feedstock in a reaction zone under catalytic crackingconditions in the absence of added hydrogen with a catalyst comprisingsaid zeolite.
 7. The process of claim 1 wherein said process is acatalytic cracking process comprising the step of contacting thehydrocarbon feedstock in a reaction zone under catalytic crackingconditions in the absence of added hydrogen with a catalyst compositioncomprising a component which is said zeolite and a large pore sizecrystalline aluminosilicate cracking component.
 8. The process of claim7 wherein the two catalyst components are incorporated in an inorganicmatrix.
 9. The process of claim 1 wherein said process is a process forisomerizing an isomerization feed containing an aromatic C₈ stream ofethylbenzene or xylene isomers or mixtures thereof, said processcomprising contacting said feed under isomerization conversionconditions with a catalyst comprising said zeolite.
 10. The process ofclaim 9 wherein said zeolite contains a Group VIII metal component. 11.The process of claim 10 wherein said Group VIII metal is platinum,palladium or nickel.
 12. The process of claim 9 wherein said aromatic C₈mixture contains ethylbenzene, para-xylene, meta-xylene, andortho-xylene.
 13. The process of claim 9 further comprising recoveringan isomerization product having an enhanced paraxylene content and areduced ethylbenzene content relative to the isomerization feed.
 14. Aprocess for the catalytic conversion of lower aliphatic alcohols having1 to 8 carbon atoms to form gasoline boiling range hydrocarbons, saidprocess comprising contacting the alcohols under converting conditionswith a zeolite having a mole ratio of silicon oxide to aluminum oxidegreater than about 20:1 to less than 40:1, and having the X-raydiffraction lines of Table
 1. 15. The process of claim 14 wherein thealcohol is methanol.
 16. The process of claim 14 wherein said zeolite ispresent in the form of H-SSZ-32.